5 Things That Make Living with a Carburetor Easier

A properly running car is a finely tuned system of parts working in harmony. Any component, then, can make the difference between a running and driving machine and a coughing, spitting garage ornament. If one critical component is a bit persnickety, it often earns a bad reputation it may not deserve. If you know (or are) someone who’s into old cars, you probably know the love/hate affair with carburetors.

We all know the holy trinity of engine worship: Fuel, air, and spark. These three elements must exist in the right proportions for an engine to run. Because “holy quaternary” just doesn’t have the same ring to it, compression gets shoved off into the corner, to be discussed only by those who have ascended to a higher tier of diagnostics beliefs, like that guy with the long beard who is still remarkably adept at spark plug reading. He diagnosed a distributor gasket leak from across the parking lot once. I was there.

Maybe I’m misremembering, but it’s precisely that kind of guru mechanic people picture when want someone to work on their carburetor. It doesn’t take a wizard to have a great-running carbureted car, however. Just about anyone can have it. To get there and stay there takes a little bit of care, but the basics boil down to five things.

Use Clean, Non-Ethanol Fuel

Although ethanol-blended fuel does have big power potential, it is also the root of more than a few headaches for those of us with a vintage bent. Gasoline will evaporate at the temperatures most of us like to cruise in, and that means the gasoline disappears and leaves the residue of the ethanol behind. It clogs the multitude of precision passages that make a carburetor function. Most carb tuning and advice is rooted in pre-ethanol times, so even using jetting and setup advice can be tough, as ethanol fuel behaves differently compared to “pure” gasoline.

A Well-Tuned Choke

Listen to the arguments against carbs, and cold starts are oft cited as being a runaway victory for fuel injection. It’s a fair point; fuel injection has won the smooth-running game handily, but a well-tuned choke on a carb works really well considering how simple it is. After all, it carried us through when our hobby cars were simply daily drivers.

Thermostatic chokes often use a bimetallic coil, which is just two different metals bonded together that expand differently when heated or cooled. Pump the throttle once before starting the engine to set the choke, and the engine should start and set at a high idle. Consult your shop manual to get exact settings. Tuning a choke can be finicky, but when it’s all sorted, there is nothing quite like a smooth start-up on a crisp fall morning.

Happy Distributor

A professor of mine from college once told me “90 percent of your fuel problems are ignition.” People will be chasing “carb problems” for hours before realizing the damp spark plug that seems to be running too rich is actually just a plug getting weak spark or not firing at all. Keeping the ignition in top shape helps to keep many other components running smoothly—and it also assists with diagnostics for rough running.

Smooth Linkages

Binding linkages can make chokes stick and accelerator pumps function inconsistently. It’s wild to think that the carb’s exterior cleanliness is just as critical as its cleanliness inside. Road grime is attracted to oily or damp surfaces, and it only takes a small amount of oil mist from an open breather or leaky gasket to attract a surprising amount of junk, which will damage small seals or gum up finicky linkages.

Clean Air

It seems there are actually three sides to a carburetor: the fuel side, the air side, and the outside. Does that make sense? Maybe. Regardless, the air coming into an engine is the easiest pathway for all the stuff that should stay outside of an engine to get inside of it. Dirty throttle blades and intake manifolds can cause interesting problems in both carbureted and fuel-injected engines. All the delicate and small air passages that help keep carbs balanced and flowing can get clogged quickly. Keep an air filter on the intake, and your carb will be happy for a long time.

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